Replication tooling has been produced by several different techniques. These techniques include, for instance, machining and lithographic processing. Machining is accomplished by cutting with a stylus or microdrilling into a substrate. Devices which accomplish such machining are either manually, mechanically, or electronically controlled. These devices are capable of producing surfaces with optical grade precision, depending upon their quality. Examples of such devices include a diamond stylus and a microdrill.
Another method for the production of structured tooling relates to the use of sharpened or shaped structures, such as pins or rods, being forced into a relatively soft medium. For example, a traditional, multi-step approach to the production of a replication molding or tooling involves the preparation of a primary negative mold by forcing the structures into a relatively soft medium. Intermediate positive master molds are made from the negative primary mold and are then joined together to form a large positive mold. A large negative mold is then produced from the large positive mold, which is then used to produce replicated articles.
Mechanical methods are effective and economical for many kinds of structure generation. However, they can be expensive and time-consuming for the generation of very small structures.
Lasers have been used to machine some finished articles, including molds or replication toolings. Other methods include UV, X-ray, and electronic beam lithography. Usually, these methods are expensive when small structures with high resolution need to be produced. Some of them have the limitation that only small sample sizes can be produced.
Some replication applications require optical quality surfaces, which necessitates the use of costly production devices. However, there is a growing number of applications that do not require optical quality tooling since a precisely manufactured article surface is not required.
The present invention provides methods for replicating a structured surface. In one embodiment, a method includes: providing a tool that includes a structured surface having a surface morphology of a crystallized vapor deposited material; and replicating the structured surface of the tool to form a replicated article. As used herein, a xe2x80x9creplicated articlexe2x80x9d is separable from the tool, preferably substantially in tact such that if desired it can become a tool for further replication, although it need not be further replicated. Preferably, the method further includes separating the replicated article and the tool.
In one embodiment, the structured surface of the tool includes the crystallized vapor deposited material itself, whereas in an alternative embodiment the structured surface of the tool includes a replica of the crystallized vapor deposited material. In another embodiment, the tool consists essentially of the crystallized vapor deposited material, whereas in an alternative embodiment the tool includes a substrate on which is disposed the crystallized vapor deposited material or a replica of the crystallized vapor deposited material.
In yet another embodiment, the step of providing a tool includes: providing a substrate that includes a surface; and depositing a material on the surface of the substrate using a vapor deposition technique to form a tool that includes a structured surface having a crystallized vapor deposited material on the substrate. The vapor deposition technique can be a chemical or a physical vapor deposition technique, for example, although a chemical vapor deposition technique is preferred. The substrate can be any of a wide variety of substrates, including planar substrates, such as sheet materials, or cylindrical substrates, for example. The surface of the substrate may be nonplanar, including other microstructures or macrostructures.
In still another embodiment, the step of providing a tool includes: providing a substrate that includes a surface; depositing a material on the surface of the substrate using a vapor deposition technique to form a crystallized vapor deposited material; and separating the crystallized vapor deposited material from the substrate surface to form the tool. Preferably, the vapor deposition technique is a chemical vapor deposition technique.
As used herein, the phrase xe2x80x9csurface morphology of a crystallized vapor deposited materialxe2x80x9d means that the shapes and sizes of the structures result directly from the crystallization process (i.e., they are formed from crystallization of the vapor deposited material), thereby forming a master tool, or as a result of replicating another surface from a master tool, for example. This morphology typically includes randomly positioned structures having sizes that vary over a wide range to include both nanostructures (e.g., those on a nano-scale) and microstructures (e.g., those on a micro-scale), preferably having a substantially continuous distribution. Generally, the range of sizes depends on the deposition method and the conditions for deposition (e.g., the rate and time of deposition). Preferably, the structured surface includes randomly positioned structures having an average size (i.e., the average of the longest dimension of the base of a structure, such as a diameter of a circular base) of at least about 10 nanometers (nm), and an average spatial distance between two adjacent structures of at least about 10 nm. Preferably, the structured surface includes randomly positioned structures having an average size of no greater than about 50,000 nm, and an average spatial distance between two adjacent structures of no greater than about 50,000 nm. The tool can be made using a substrate that has macrostructures (or microstructures) prior to vapor depositing. The resultant tool has structures on structures (e.g., microstructures on macrostructures).
The tool can be replicated using a wide variety of techniques. These include, for example: casting a curable composition on the structured surface of the tool and at least partially curing the composition on the structured surface of the tool; embossing the article with the structured surface of the tool; injection molding a polymeric material onto the structured surface of the tool; extruding a material onto the structured surface of the tool and hardening the material on the tool; electroforming a material onto the structured surface of the tool; or vapor depositing a second material onto the structured surface of the tool.
As stated above, the replicated article can be used as a tool for further replication, if desired. The replicated article can have a surface that is the negative of the surface of the tool, or it can have one surface that is the negative of the surface of the tool and another surface that is the positive of the surface of the tool. The positive or negative replica of the surface can be used as the surface of the replicated article that can be further replicated. The replicated article optionally can be physically deformed before using it as a tool for further replication. It can also be treated, as with a fluorochemical, for example, before being used as a tool for further replication.
In a preferred method of replicating a structured surface, the method includes: providing a substrate; chemical vapor depositing a material that includes a metal on the substrate to form a master tool having a structured surface formed from crystallization of the chemical vapor deposited material; replicating the structured surface of the master tool to form a replicated article; and separating the master tool and the replicated article. In another preferred method of replicating a structured surface, the method includes: providing a substrate; chemical vapor depositing a material that includes nickel on the substrate to form a master tool having a structured surface formed from crystallization of the chemical vapor deposited material; replicating the structured surface of the master tool to form a replicated article; and separating the master tool and the replicated article.
The methods of the present invention can be used to alter the affect of a surface on a fluid (e.g., a gas or a polar or nonpolar liquid such as water or oil). Thus, the present invention provides a method of altering the affect of a surface on a fluid. The method includes: providing a tool that includes a structured surface having a surface morphology of a crystallized vapor deposited material; providing an article having a surface; replicating the structured surface of the tool in the surface of the article to form a replicated article; and separating the tool and the replicated article, wherein the affect of the replicated surface of the article on a fluid is altered. In one preferred embodiment, the method includes: providing a tool that includes a structured surface having a surface morphology of a crystallized vapor deposited material; providing an article having a hydrophobic surface; replicating the structured surface of the tool in the hydrophobic surface to form a replicated article; and separating the tool and the replicated article, wherein the hydrophobicity of the hydrophobic surface of the replicated article is increased. In another preferred embodiment, the method includes: providing a tool that includes a structured surface having a surface morphology of a crystallized vapor deposited material; providing an article having a hydrophilic surface; replicating the structured surface of the tool in the hydrophilic surface to form a replicated article; and separating the tool and the replicated article, wherein the hydrophilicity of the hydrophilic surface of the replicated article is increased.
The present invention also provides a replicated article that includes at least one replicated surface, wherein the replicated surface includes a replica of a crystallized vapor deposited material. The replicated article can be in the form of a sheet material such as a film. Preferably, the replicated surface includes a replica of a crystallized chemical vapor deposited material or a crystallized physical vapor deposited material.
The present invention also provides a replication tool that includes: a tool body that includes a tooling surface; and a structured surface on the tooling surface, wherein the structured surface includes crystallized vapor deposited material or a replica of crystallized vapor deposited material. The tooling surface can be planar or nonplanar. The tool body can be in a variety of shapes, such as a cylinder, which is preferred for use in a continuous replication process. The crystallized vapor deposited material can be physical or chemical vapor deposited material. The tool body preferably consists essentially of the crystallized vapor deposited material, although it can be disposed on a substrate.
In a preferred embodiment, the replication tool includes: a tool body that includes a cylinder having a tooling surface; and a structured surface on the tooling surface, wherein the structured surface includes crystallized chemical vapor deposited material or a replica of crystallized chemical vapor deposited material.